May 1, 2004

Mold and Bath Fans

I remodeled and built many homes in the twenty years I was working in the field. One thing I always questioned was the use of a soffit vent hood for a bathroom or kitchen exhaust fan. It was my opinion this method of venting humid air was a huge mistake.

The large cloud of water vapor could easily be drawn into the attic and be the trigger for massive amounts of mold growth. If you have any spare time, stop by your local clerk of courts and see how many mold-related lawsuits have been filed in your area in the past several years. Mold is indeed a buzzword in the litigation and insurance industry.

Mold needs water, favorable temperatures and a food source in order to blossom and grow. Mold can grow in a wide range of temperatures. It can thrive in just about all of the temperatures we tolerate including colder temperatures. Water vapor being pulled into an attic through nearby soffit vents will initiate mold growth in almost all situations as the roof sheathing is covered with food thgat will support mold growth.

If you are getting ready to build or remodel make sure your bath fan vents through the roof. The fan manufacturers make special leak-proof roof caps for this explicit purpose. These roof caps are equipped with a flapper to minimize drafts. I have installed many and all of my customers are very pleased with them.